<!DOCTYPE html>
<head>
    <meta charset="UTF-8">
    <title>...</title>
    <style>
        h1{
            color: red;
        }
        body{
            /* body选择器限制不了h1的字体，*选择器可以*/
            font-size: 16px;
            color:green;
        }
        *{
            font-size: 50px;
            color:green;
        }
        .blue{
            color:blue;
        }
        .size{
            font-size: 60px;
        }
    </style>
</head>
<body>
    <h1 >这是标题一</h1>
    <p>这是正文一</p>
    <h1 class="blue size ">这是标题二</h1>
    <p>这是正文二</p>
    <h1>这是标题三</h1>
    <p>这是正文三</p>
</body>
</html>